Doc update for new db migration

docs/development.md

@@ -9,9 +9,25 @@ To run this application locally:
 3. Run `npm i`, and then `npm run setup` to perform initial setup
 4. Start a dev server using `npm run dev`
 
+## If there is a database schema update
+
+If you're getting an error that looks like this:
+
+```
+Invalid `prisma.user.findFirst()` invocation:
+
+
+The column `main.User.mailingList` does not exist in the current database.
+```
+
+There's a new DB update and you'll need to trigger a Prisma schema update via
+`prisma migrate deploy`. This looks at `prisma/migrations` and will update your
+local database.
+
 ## Add a new admin user
 
-To do this, it's easiest to use Prisma studio, which gives you access to the sqlite database through a web UI.
+To do this, it's easiest to use Prisma studio, which gives you access to the
+sqlite database through a web UI.
 
 1. `npx prisma studio`
 2. Head over to http://localhost:5555/